You asked about the stamp - it appears to be Scott #634 which is a very common stamp. There are a number of varieties of this stamp but you would need to look really closely with a list of the differences to tell which variety it may be - though there is something like 99.99 percent chance that this is going to be the most common. You should get a copy of the US Specialized Scott Catalog to see the differences and even then it is not easy to tell the differences without some experience. Here is a link to an eBay
auction (not mine and I do not know the seller) that is offering 100 used examples of 634 for $3.50 buy it now and there does not appear to be a rush of people trying to buy it. That comes out to about 3 and a half cents per stamp. https://www.ebay.com/itm/100-USED-S...AOxy0bRTFWIX
As for the inverted year in the cancel, as was already stated this is not uncommon and is simply the result of a careless postal worker that day in that post office and as such carries no premium.